fix(redact): preserve Codex input_image payloads during JSONL redaction

redact/redact.go

@@ -1049,10 +1049,27 @@ func shouldSkipJSONLField(key string) bool {
 	return false
 }
 
-// shouldSkipJSONLObject returns true if the object has "type":"image" or "type":"image_url".
+// codexImageTypes are the exact "type" values Codex uses for embedded
+// screenshots. Matched by explicit equality (not a "_image" suffix) so an
+// unrelated object shape that happens to end in "_image" (e.g. a
+// "docker_image"/"container_image" record carrying a real secret in another
+// field) is not skipped.
+var codexImageTypes = map[string]bool{
+	"input_image":  true,
+	"output_image": true,
+}
+
+// shouldSkipJSONLObject returns true if the object represents an image payload:
+// "type":"image" or "type":"image_url" (Claude/OpenAI chat format), one of
+// codexImageTypes (Codex embeds screenshots this way), or "type":"base64".
+// Image data is high-entropy binary, not a secret — redacting it would
+// corrupt the payload.
 func shouldSkipJSONLObject(obj map[string]any) bool {
 	t, ok := obj["type"].(string)
-	return ok && (strings.HasPrefix(t, "image") || t == "base64")
+	if !ok {
+		return false
+	}
+	return strings.HasPrefix(t, "image") || codexImageTypes[t] || t == "base64"
 }
 
 func shannonEntropy(s string) float64 {

redact/redact_test.go

@@ -96,6 +96,34 @@ func TestJSONLBytes_WithSecret(t *testing.T) {
 	}
 }
 
+func TestJSONLBytes_CodexInputImage_PreservesBase64(t *testing.T) {
+	// Codex embeds images as "type":"input_image" with a data URL. Before the
+	// fix, shouldSkipJSONLObject only matched "image"-prefixed types, so this
+	// high-entropy base64 payload was silently destroyed into "REDACTED".
+	input := []byte(`{"type":"input_image","image_url":"data:image/png;base64,` + highEntropySecret + `"}`)
+	result, err := JSONLBytes(input)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if string(result.Bytes()) != string(input) {
+		t.Errorf("expected input_image payload unchanged, got %q", result.Bytes())
+	}
+	if strings.Contains(string(result.Bytes()), RedactedPlaceholder) {
+		t.Errorf("expected no redaction of input_image payload, got %q", result.Bytes())
+	}
+}
+
+func TestJSONLBytes_ClaudeImage_StillPreserved(t *testing.T) {
+	input := []byte(`{"type":"image","source":{"data":"` + highEntropySecret + `"}}`)
+	result, err := JSONLBytes(input)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if string(result.Bytes()) != string(input) {
+		t.Errorf("expected image payload unchanged, got %q", result.Bytes())
+	}
+}
+
 func TestRedactedBytes_Bytes(t *testing.T) {
 	t.Parallel()
 	input := []byte(`{"type":"text","content":"hello"}`)
@@ -1252,6 +1280,26 @@ func TestShouldSkipJSONLObject(t *testing.T) {
 			obj:  map[string]any{"type": "base64"},
 			want: true,
 		},
+		{
+			name: "input_image type is skipped",
+			obj:  map[string]any{"type": "input_image", "image_url": "data:image/png;base64,abc"},
+			want: true,
+		},
+		{
+			name: "output_image type is skipped",
+			obj:  map[string]any{"type": "output_image"},
+			want: true,
+		},
+		{
+			name: "docker_image type is NOT skipped (only exact Codex image types match)",
+			obj:  map[string]any{"type": "docker_image", "url": "https://token@registry"},
+			want: false,
+		},
+		{
+			name: "container_image type is NOT skipped",
+			obj:  map[string]any{"type": "container_image"},
+			want: false,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {